jekyll-verison-helper

This gem lets you define variables within a _config.yml file and refer to it through the same file.

To do that, first, create a key called variables, and populate it with any set of variable names you like:

variables:
  latest_version: "2.0"

In this case, a new variable called latest_version is available to use, and it's defined a "2.0". You can use this variable throughout your YAML file with the %{...} notation. For example:

defaults:
  -
    scope:
      path: ""
      type: "source"
      values:
        version: "%{latest_version}"

This sets a frontmatter of version on all the files in the source collection. It uses whatever value is defined in latest_version to set that up.